|Publication number||US7725468 B2|
|Application number||US 10/908,666|
|Publication date||May 25, 2010|
|Filing date||May 22, 2005|
|Priority date||Apr 8, 2005|
|Also published as||US7925617, US20060230020, US20100191730|
|Publication number||10908666, 908666, US 7725468 B2, US 7725468B2, US-B2-7725468, US7725468 B2, US7725468B2|
|Original Assignee||Oracle International Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (43), Classifications (6), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates generally to processing queries directed to large data sets, and more specifically to a method and apparatus for improving efficiency in processing queries directed to static data sets.
2. Related Art
Queries are often directed to data sets. For example, an SQL query contains select statements which are intended to retrieve only the data items of interest from a large data set.
Static data sets are created in some environments. Static data sets refer to data sets, which are unlikely to change at least in a reasonably long duration. Data warehouses are example environments in which static data sets are found.
There is a general need to quickly process queries directed to static data sets. For example, a quick response time may be provided to users due to the ability to process queries quickly.
The present invention will be described with reference to the accompanying drawings briefly described below.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.
A server provided according to an aspect of the present invention maintains data indicating which rows match each condition of interest. The maintained data can then be quickly used to determine the specific rows that match each subsequently received query if such queries contain the conditions of interest. As a result, queries can be processed quickly.
According to another aspect of the present invention, the server examines each received query to determine commonly occurring conditions, and uses such commonly occurring conditions as conditions of interest. Thus, at least for repeating conditions, the queries may be processed quickly.
The features are particularly useful in which the data sets are static (e.g., in data warehousing applications). However, when the data sets change, the data indicating the rows matching each condition of interest may be updated accordingly. Such processing can potentially be performed off-line so that responses to queries can be provided quickly.
Several aspects of the invention are described below with reference to examples for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One skilled in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details, or with other methods, etc. In other instances, well-known structures or operations are not shown in detail to avoid obscuring the features of the invention.
2. Example Environment
Network 120 provides the connectivity between various systems using protocols such as Internet Protocol (IP). Database client 110 sends transaction requests to database server 130, for example, when executing user applications. The transaction requests generally indicate the corresponding instructions to be executed on database server 130 and any values required to process the instructions.
Database server 130 processes the received transaction request and alters (add, delete and change) the data in database storage 140. Multiple databases (each database containing multiple tables potentially) may be saved in database storage 140 as a result. The data in each database may be viewed as a data set. Such data sets are often transferred to data warehouses once the transactions ‘mature’ (e.g., completion of a sale).
Data warehouse 150 generally stores static data sets. The data sets may be received from database storage 140, as noted above. Warehouse client 170 sends query requests to warehouse server 190 on network 120. In general, each query contains a set (zero, one or more) of conditions.
Warehouse server 190 processes query requests received from warehouse client 170 by accessing the static data set in data warehouse 150, and sending back the matching (and requested) data. Various aspects of the present invention enable warehouse server 190 to process query requests quickly. The corresponding features will be clearer in comparison to a prior approach, which does not use one or more of the features of the present invention. Accordingly, the corresponding prior approach is described first below.
3. Prior Approach
When a condition contains age, a server searches the table of
One problem with the above technique is that the server may make several accesses to the table of
Such multiple accesses may lead to slower response times due to the processing and access requirements. Various features of the present invention overcome such disadvantages, as described below in further detail.
4. Efficient Query Processing
In step 310, a data-warehouse containing multiple rows of data with corresponding row identifiers is created in data warehouse 150. Multiple rows of data are created from data sets received from database storage 140 assuming the data is organized in the form of relational data bases.
In step 320, warehouse server 190 identifies conditions which can be included in queries to the data-warehouse. Query requests sent from warehouse client 170 generally include conditions while accessing specific data sets. Warehouse server 190 may identify such conditions from queries received over a pre-determined time. Alternatively or in addition, the an administrator may specify the conditions. The identified conditions may be stored in data warehouse 150.
In step 330, warehouse server 190 determines which rows match which of the conditions identified in step 320. The rows created in data warehouse 150 may be accessed and examined to determine the rows that match each condition. In step 340, warehouse server 190 maintains data indicating which rows meet each condition. One approach to maintaining of data indicating rows that meet specific conditions is described below with reference to
In step 350, warehouse server 190 receives a query containing a condition from warehouse client 170. In step 360, warehouse server 190 determines if the condition in the received query is present in the conditions identified in step 320. If the condition in the query received is present in the conditions identified in step 320, control passes to step 370 and to step 375 otherwise.
In step 370, warehouse server 190 examines the data of step 340 to determine the rows matching the condition. Since data is maintained indicating the rows matching each condition (in step 340), ware house server 190 can determine rows matching the condition of step 350 by accessing the data maintained in step 340. Control then passes to step 380.
In step 375, warehouse server 190 determines rows matching the condition in the query by accessing data-warehouse 150. Since conditions in the received query is not identified earlier, larger number of rows in data warehouse 150 may be accessed as compared to such an operation performed in step 370, to determine rows matching the condition of step 350. The information (rows matching for the condition) thus determined can be used to update the data of step 340 (now shown). Control then passes to step 380.
In step 380, warehouse server 190 generates a response to the query according to the matching rows and may send the response to warehouse client 170. In step 385, warehouse server 190 determines whether another query request is received from warehouse client 170. Control passes to step 360 if another query request is received, or to step 390 otherwise.
In step 390, warehouse server 190 determines if there are any changes to data sets in data warehouse. Such determination may be performed techniques such as scheduling of update activities in warehouse server 190. Control passes to step 320, if there are changes or to step 399 otherwise, where the program ends.
It may be appreciated that step 340 can be performed off-line (i.e., before queries are received), and then the responses can be generated quickly if the conditions in query are contained in the conditions identified in step 320. Thus efficiency of processing of queries directed to data sets is improved.
The description is continued with respect to the manner in which data is maintained to indicate the rows matching each identified condition, in an embodiment of the present invention.
5. Rows Matching Each Condition
The table of
Similarly, rows 221-225 match condition C2 (row 422) and data is accordingly maintained in corresponding rows of 521-525. Other conditions that each row matches are identified by examining the rows of
As a further throughput performance enhancement, the data of
Thus, when a query containing condition as indicated in row 421 is received from warehouse client 170, warehouse server 190 identifies corresponding condition identifier and later examines data maintained according to
From the above, it may be appreciated that the number of access is reduced, at least in comparison to the prior approaches noted above. As noted above, the number of accesses to determine matching rows (based on an indexed column) in a B-tree type model is of the order of log 2(N) (N representing the number of rows), whereas the number of accesses (while processing a query in real-time) according to the approaches of
It should also be appreciated that the features of the present invention are described above with respect to a single table and a simple conditions merely for illustration. However the approaches can be extended in the context of complex conditions (each complex condition potentially containing multiple conditions) and also to large data sets (e.g., multiple tables), without departing from the scope and spirit of the present invention, as will be apparent to one skilled in the relevant arts.
It should also be appreciated that the features described above can be implemented in various embodiments. The description is continued with respect to an embodiment in which various features are operative when software instructions are executed.
6. Digital Processing System
CPU 610 may execute instructions stored in RAM 620 to provide several features of the present invention. CPU 610 may contain multiple processing units, with each processing unit potentially being designed for a specific task. Alternatively, CPU 610 may contain only a single general purpose processing unit. RAM 620 may receive instructions from secondary memory 630 using communication path 650.
Graphics controller 660 generates display signals (e.g., in RGB format) to display unit 670 based on data/instructions received from CPU 610. Display unit 670 contains a display screen to display the images defined by the display signals. Input interface 690 may correspond to a key-board and/or mouse. Network interface 680 provides connectivity to a network (e.g., using Internet Protocol), and may be used to communicate with the other systems of
Secondary memory 630 may contain hard drive 635, flash memory 636 and removable storage drive 637. Secondary memory 630 may store the data and software instructions (e.g., methods instantiated by each of client system), which enable system 600 to provide several features in accordance with the present invention. Some or all of the data and instructions may be provided on removable storage unit 640, and the data and instructions may be read and provided by removable storage drive 637 to CPU 610. Floppy drive, magnetic tape drive, CD-ROM drive, DVD Drive, Flash memory, removable memory chip (PCMCIA Card, EPROM) are examples of such removable storage drive 637.
Removable storage unit 640 may be implemented using medium and storage format compatible with removable storage drive 637 such that removable storage drive 637 can read the data and instructions. Thus, removable storage unit 640 includes a computer readable storage medium having stored therein computer software and/or data.
In this document, the term “computer program product” is used to generally refer to removable storage unit 640 or hard disk installed in hard drive 635. These computer program products are means for providing software to system 600. CPU 610 may retrieve the software instructions, and execute the instructions to provide various features of the present invention described above.
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. Also, the various aspects, features, components and/or embodiments of the present invention described above may be embodied singly or in any combination in a data storage system such as a database system and a data warehouse system.
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|U.S. Classification||707/736, 709/224|
|International Classification||G06F15/173, G06F17/30|
|May 22, 2005||AS||Assignment|
Owner name: ORACLE INTERNATIONAL CORPORATION,CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MISHRA, AMULYA;REEL/FRAME:016048/0699
Effective date: 20050414
|Oct 30, 2013||FPAY||Fee payment|
Year of fee payment: 4